Ship safety and fire fighting

In short

Ship safety and fire fighting covers how fire is prevented, detected, contained and extinguished on board, and how crew and passengers are protected and evacuated when prevention fails. A ship is an isolated steel box with large fuel oil quantities, hot surfaces, confined spaces and no fire brigade to call, so statutory requirements are unusually prescriptive — SOLAS Chapter II-2 (fire), Chapter III (life-saving appliances) with the LSA Code, the FSS Code and the ISM Code. In India these are enforced through the Merchant Shipping Act, 2025 (in force 15 March 2026; it repealed the 1958 Act) and rules made under it, administered by the Directorate General of Shipping (DG Shipping, renamed the Directorate General of Maritime Administration, DGMA, in 2026) and recognised classification societies such as the Indian Register of Shipping. The topic is examined in marine engineering ship safety / fire fighting papers, in the DG Shipping competency examinations and STCW mandatory courses (Basic and Advanced Fire Fighting, Personal Survival Techniques), and is asked in almost every interview for sea-going and shipyard jobs with SCI, Great Eastern Shipping, Essar, Synergy, Anglo-Eastern, Fleet, Cochin Shipyard and Mazagon Dock.

Explained

Fire theory and classification

• Fire triangle: fuel + oxygen + heat (ignition energy). Removing any one side extinguishes fire — cooling (water), smothering (CO₂, foam), starvation (shutting fuel valves). The fire tetrahedron adds the uninhibited chain reaction, broken chemically by dry powder and clean agents.
• Flash point: lowest temperature at which a liquid gives off enough vapour to flash momentarily on an ignition source. Bunkers for marine use must have flash point above 60 °C (closed-cup, Pensky-Martens) under SOLAS; a lower value is permitted only for emergency generator fuel (43 °C) in specific arrangements.
• Fire point: a few degrees above flash point, where burning sustains. Auto-ignition temperature: ignites without a flame — the hazard of oil on hot exhaust lagging.
• Flammable limits (LEL/UEL): a vapour-air mixture burns only between them; hydrocarbon cargo tanks are kept inert below 8% oxygen so no mixture can burn.
• Classes of fire (Indian/IS and IMO practice):
  • Class A — solids leaving embers (wood, bedding, dunnage): water, cooling.
  • Class B — flammable liquids (fuel, lube oil, paint): foam, CO₂, dry powder, water spray/fog.
  • Class C — flammable gases (LPG, cargo vapour): shut off supply, cool, dry powder.
  • Class D — combustible metals (magnesium anodes, aluminium swarf): special powders, never water.
  • Class E (electrical, Indian usage) — non-conducting media: CO₂, dry powder; isolate first.
  • Class F / K — cooking oils and fats in the galley: wet chemical (saponification), never water.
• Modes of heat transfer in a ship fire: conduction through steel decks and bulkheads (a fire can spread by hot plating alone — hence boundary cooling), convection up stairways and trunks, radiation to adjacent surfaces.

Fire prevention and structural protection

• Housekeeping: no oil-soaked rags, bilges and tank tops clean, lagging on hot surfaces intact and oil-free, save-alls and drip trays in place, spray shields and anti-splash tape on fuel lines above 60 °C surfaces.
• High-pressure fuel line protection: jacketed piping on diesel engines with an alarmed leak-collection system — the standard answer to engine-room oil-mist fires.
• Hot work control: permit to work, gas-free certificate, enclosed-space entry checks, fire watch kept during and after welding; a major item in ISM safety management systems.
• Structural fire protection: divisions classified by their fire test performance —
  • "A" class: steel, insulated so the unexposed face stays below the limit for A-60/A-30/A-15/A-0 minutes; stops smoke and flame for 60 min.
  • "B" class: non-combustible, flame-tight for 30 min, insulated to B-15/B-0.
  • "C" class: non-combustible, no integrity or insulation requirement.
  • "H" class: hydrocarbon fire rating used on offshore installations.
• Means of escape: two from every space, continuous low-location lighting on passenger ships, escape trunks from the engine room, self-closing fire doors held on fusible links or remote release.
• Ventilation and openings: remote stops for all fans, quick-closing fire dampers, skylight and funnel closures — all must be shut before CO₂ release.
• Fire control plan: permanently exhibited, and a duplicate in a prominently marked weathertight enclosure outside the deckhouse for shore fire-fighters.

Detection and alarm

• Heat detectors: fixed temperature (bimetal/fusible), rate-of-rise. Cheap and immune to steam/dust; slow. SOLAS requires fixed-temperature types to operate by about 78 °C and not below 54 °C in normal spaces.
• Smoke detectors: ionisation (fast on flaming fires) and optical/photoelectric (fast on smouldering); used in accommodation, corridors, stairways — not in galleys or engine rooms where normal smoke/oil mist gives false alarms.
• Flame detectors: infra-red or ultra-violet, fast response for boiler fronts and pump rooms.
• Sample extraction smoke detection: draws air from each cargo hold through a cabinet on the bridge — standard on dry cargo ships.
• Oil mist detectors in crankcases and bearing temperature monitoring prevent crankcase explosions; the crankcase also has relief doors (non-return, flame-arresting) and oil mist alarms.
• Alarm requirements: detection must give audible and visual alarm on the bridge or a continuously manned control station, with zone identification; manual call points (break-glass) throughout. General emergency alarm: seven or more short blasts followed by one long blast, on the ship's whistle and alarm bells.

Portable and fixed fire fighting systems

• Fire main: two independently driven main fire pumps (required on cargo ships of 1,000 GT and above; on ships of 2,000 GT and above the pumps, sea suctions and power sources must be so arranged that a fire in any one space cannot put them all out of action), hydrants, hoses, dual-purpose jet/spray nozzles (12, 16 or 19 mm), international shore connection (one per ship, to take water from shore or another ship), isolating valve to separate the engine-room section.
• Emergency fire pump: independently driven, located outside the machinery space with its own prime mover and fuel for three hours, able to deliver two jets at required pressure with the main pumps out of action.
• Portable extinguishers: water (Class A), foam (A and B), CO₂ (B and electrical), dry chemical powder (multi-purpose), wet chemical (galley). Minimum 5 kg dry powder or 5 kg CO₂ per unit; at least five portables in accommodation/service spaces, and spare charges for 100% of the first ten extinguishers and 50% of the remainder (maximum 60 spares) where they can be recharged on board, otherwise the same number of additional extinguishers of each type.
• Fixed gas (CO₂) total flooding for machinery spaces, pump rooms and cargo holds: quantity for machinery spaces normally 40% of gross volume of the largest space (or 35% including the casing, whichever is greater); cargo holds 30%. Release requires two distinct actions, an audible alarm and 20 s pre-discharge delay in manned spaces, with 85% of the gas delivered in 2 minutes for machinery spaces. All openings shut, fans stopped, personnel accounted for, space kept closed for hours before boundary cooling and controlled re-entry.
• Alternatives to CO₂: high-expansion foam, water mist (local and total), and clean agents (HFC-227ea, inert gas blends) — halon is banned for new installations under the Montreal Protocol and SOLAS.
• Local application water mist/foam ("local fixed fire fighting") required in category A machinery spaces over 500 m³, aimed at boiler fronts, purifiers, main engine top and incinerator — it can be used with the space manned.
• Foam systems: low-expansion deck foam for tankers (monitors and hand hoselines; foam to cover the tank deck for 20 min typically), high-expansion foam for machinery spaces and pump rooms. Foam works by smothering, cooling and sealing vapour; AFFF forms an aqueous film. Alcohol-resistant foam for polar solvents; never use foam on live electricals.
• Water spray and sprinkler systems: automatic sprinklers (bulb bursts at about 68 °C typically, range 68-79 °C) in accommodation of passenger ships and many cargo ships, with a pressure tank, pump and zone flow alarms. Drencher systems on ro-ro decks.
• Inert gas system (tankers): flue gas or inert gas generator, scrubber, blowers, deck water seal, non-return valve, P/V breaker; keeps tank oxygen below 8% by volume and tanks at positive pressure. Mandatory on oil tankers of 8,000 DWT and above (newer ships; older thresholds were higher).
• Fireman's outfit: SCBA (normally 1,200 litres air / 30 min minimum), spare charged cylinder, lifeline and belt, fire-resistant protective clothing, boots, gloves, helmet, electric safety lamp (3 h) and fire axe. EEBDs (emergency escape breathing devices, minimum 10 min) in machinery spaces and accommodation — escape only, never for fire fighting.

Life-saving appliances and emergency response

• Survival craft: lifeboats (totally enclosed, free-fall on many bulk carriers and tankers; fire-protected on tankers), liferafts (throw-overboard or davit-launched, with hydrostatic release unit that frees the raft at about 1.5-4 m depth), rescue boat (one, may be a lifeboat if it meets both sets of requirements).
• Capacity rule of thumb (cargo ships): survival craft on each side for the total number of persons, or free-fall lifeboat aft for all persons plus liferafts on each side for all persons; plus lifebuoys and lifejackets for all with extras for watchkeepers and distributed stowage.
• Personal appliances: lifejacket with light and whistle, immersion suit for each person (TPAs on some ships), lifebuoys with self-igniting light and self-activating smoke signal, line-throwing appliance with four lines and projectiles.
• Distress and location: EPIRB (406 MHz, float-free), two-way VHF radiotelephones (three on larger ships), SART/AIS-SART, rocket parachute flares (12), hand flares, buoyant smoke signals — all part of GMDSS/LSA requirements.
• Drills and training: abandon ship and fire drills within 24 hours of leaving port if more than 25% of the crew changed; thereafter monthly for cargo ships (weekly musters for passengers on short voyages), each lifeboat lowered and manoeuvred in the water at least every three months, enclosed-space entry and rescue drills every two months, free-fall boat free-fall launch (or simulated launch) every six months.
• Muster list and station bill: each person's duty, alarm signals, muster stations; posted in accommodation, bridge and engine room.
• On discovering fire — standard sequence: raise alarm → inform bridge/duty officer → identify class and location → attack with the nearest suitable appliance if safe → boundary cooling → close openings and stop ventilation → account for all personnel → alter course to put the fire leeward → only then consider fixed flooding.

Indian statutory framework and management systems

• Merchant Shipping Act, 2025 (in force 15 March 2026; it repealed the Merchant Shipping Act, 1958) gives SOLAS effect in Indian law through its safety and security Part (sections 114-130, including safety and security requirements, s.116, and the bar on proceeding to sea without valid safety and security certificates, s.124) and the 2026 rules made under it — the Cargo Vessel and Passenger Ship Construction, Fire Appliances and Survey Rules, the Life-Saving Appliances and Arrangements Rules and the Safety Management Rules; DG Shipping (now DGMA) issues circulars and is the flag administration.
• Certificates: Cargo Ship Safety Construction, Cargo Ship Safety Equipment, Cargo Ship Safety Radio (or a single Cargo Ship Safety Certificate), Passenger Ship Safety Certificate, Safety Management Certificate and Document of Compliance under the ISM Code, ISPS International Ship Security Certificate.
• ISM Code (SOLAS Chapter IX): a documented safety management system — designated person ashore, risk assessment, permits to work, emergency preparedness, reporting of non-conformities, accidents and near-misses, internal audits.
• Port State Control / Flag inspections: Indian ports operate under the Indian Ocean MoU; detainable deficiencies commonly include inoperative fire pumps, expired extinguisher and SCBA servicing, blocked escape routes and untested quick-closing valves.
• Shore and shipyard side: Occupational Safety, Health and Working Conditions Code, 2020 (in force 21 November 2025, replacing the Factories Act, 1948, the BOCW Act and the Dock Workers (Safety, Health and Welfare) Act, 1986) governs shipyard and dock work safety, with its dock-work provisions and the OSH&WC (Central) Rules, 2026; IS standards for extinguishers (portable fire extinguisher series), hydrants and foam concentrates apply ashore. Quote Indian Standards by current number only when certain — several older IS numbers for extinguishers have been superseded.
• Survey and maintenance intervals (typical): extinguishers inspected monthly and serviced annually, CO₂ cylinders weighed/level-checked annually with hydraulic testing at 10 years, SCBA cylinders hydro-tested per cylinder rules, fire detection tested weekly, hoses pressure-tested, fixed systems surveyed at class periodical surveys.

Key points

• Fire triangle - fuel, oxygen, heat; tetrahedron adds the chain reaction broken by powder and clean agents.
• Flash point - minimum temperature giving a flashable vapour; marine fuels must exceed 60 °C closed cup.
• Classes A/B/C/D/E/F - solids, liquids, gases, metals, electrical, cooking oils; media must match the class.
• A, B, C class divisions - A is steel and 60-min flame and smoke tight with insulation grades A-60 to A-0; B is 30 min; C only non-combustible.
• Two main fire pumps plus one emergency fire pump - the emergency pump sits outside the machinery space with its own power and fuel.
• International shore connection - standard flange letting shore or another ship feed the fire main.
• CO₂ total flooding - about 40% of machinery space gross volume, 30% for cargo holds; two separate actions, alarm, 20 s delay, 85% in 2 min.
• Local application system - water mist or foam on boiler fronts, purifiers and engine top; usable with the space manned.
• Inert gas - keeps tanker cargo tank oxygen below 8%, so no flammable mixture can exist.
• Sprinkler bulb - typically bursts near 68 °C; smoke detectors in accommodation, heat/flame in machinery spaces.
• Oil mist detector and crankcase relief doors - the defence against crankcase explosion.
• EEBD - escape only, minimum 10 minutes; SCBA - fire fighting, typically 1,200 litres / 30 minutes.
• Hydrostatic release unit - frees a liferaft automatically at roughly 1.5-4 m depth if the ship sinks.
• General emergency alarm - seven or more short blasts and one long blast; muster list states each person's duty.
• Drills - fire and abandon ship monthly, within 24 h of sailing after a 25% crew change; boat in water every three months.
• Fire control plan - posted on board plus a duplicate in a marked weathertight container outside the deckhouse.
• Indian regime - Merchant Shipping Act, 2025 (replaced the 1958 Act from 15 March 2026) and its 2026 rules give SOLAS, LSA, FSS and ISM effect; IRS surveys to class.
• Boundary cooling - cooling adjacent bulkheads and decks stops conducted and radiated spread even after the fire is out.

Formulas and examples

Example 1 — CO₂ charge for an engine room. Engine room 18 m long × 16 m wide × 9 m high, plus casing 6 m × 5 m × 7 m.

• Machinery space volume = 18 × 16 × 9 = 2,592 m³; casing = 6 × 5 × 7 = 210 m³; total with casing = 2,802 m³.
• Rule (a): 40% of volume excluding casing = 0.40 × 2,592 = 1,036.8 m³ of free CO₂.
• Rule (b): 35% of volume including casing = 0.35 × 2,802 = 980.7 m³. Take the greater → 1,036.8 m³.
• Mass = 1,036.8 / 0.56 = 1,851 kg (equivalently 1,036.8 × 1.80 ≈ 1,866 kg; the small difference is the density figure used — state your assumption in the exam).
• Cylinders at 45 kg: 1,851 / 45 = 41.1 → 42 cylinders.
• Resulting theoretical oxygen = 21 × (1 − 0.40) = 12.6% — below the roughly 15% needed to support most flaming combustion, and lethal to anyone left inside.

Example 2 — hydrant jet flow and pump sizing. A 19 mm nozzle at 0.27 N/mm² (2.7 bar = 2.7 × 10⁵ Pa), sea water ρ = 1,025 kg/m³, Cd = 0.97.

• A = (π/4) × 0.019² = 2.835 × 10⁻⁴ m².
• Velocity = √(2 × 2.7 × 10⁵ / 1,025) = √526.8 = 22.95 m/s.
• Q = 0.97 × 2.835 × 10⁻⁴ × 22.95 = 6.31 × 10⁻³ m³/s = 22.7 m³/h per jet (≈ 379 L/min).
• For four such jets simultaneously: 4 × 22.7 = 90.9 m³/h, so a pump rated 100 m³/h at 3 bar nozzle pressure (allowing for friction losses in the main) is adequate.
• If total main pump capacity is 100 m³/h, the emergency pump must be at least 0.40 × 100 = 40 m³/h, comfortably above the 25 m³/h floor.

Example 3 — deck foam for a crude oil tanker. Tank deck area 160 m × 32 m = 5,120 m²; largest cargo tank 32 m × 30 m = 960 m².

• Rate (a): 0.6 × 5,120 = 3,072 L/min.
• Rate (b): 6 × 960 = 5,760 L/min → governing rate = 5,760 L/min of foam solution (the largest-monitor rate must also be checked, subject to the 1,250 L/min floor).
• Solution for 20 min (ship with inert gas) = 5,760 × 20 = 115,200 L.
• At 3% induction, concentrate = 0.03 × 115,200 = 3,456 litres (about 3.5 m³ of foam compound) — hence the sizeable deck foam tank; at 6% it would be 6,912 litres.

Example 4 — cooling power of water. A hose delivers 379 L/min (Example 2) of sea water at 28 °C onto a Class A fire.

• As a jet, only the sensible heat to 100 °C is used: m = 379 kg/min = 6.32 kg/s; Q = 6.32 × 4.18 × 72 = 1,902 kW.
• If fully converted to steam as fog: Q = 6.32 × (4.18 × 72 + 2,257) = 6.32 × 2,558 = 16,167 kW — about 8.5 times more heat removed from the same water.
• Steam expansion also smothers: 1 litre of water makes roughly 1,700 litres of steam at atmospheric pressure, which is why fog in a confined space must be used with care.

Example 5 — inerting a cargo tank. A 12,000 m³ tank at 21% oxygen is to be inerted to 5% using inert gas containing 2% oxygen, assuming perfect dilution (mixing) and a dilution factor of about 2.5 tank volumes for the practical case.

• Ideal displacement requirement (plug flow): 1 tank volume = 12,000 m³.
• Dilution (mixing) method: volumes ≈ 2.5 × 12,000 = 30,000 m³ of inert gas.
• At a blower capacity of 5,000 m³/h, time = 30,000 / 5,000 = 6 hours. Exam answers must state which model (displacement or dilution) is assumed, since the gas quantity differs by more than a factor of two.

Where it is used

• Sea-going engineers and officers: maintaining fire pumps, quick-closing valves, detectors, CO₂ bottles and LSA; running drills and inspections with SCI, Great Eastern Shipping, Essar Shipping, Synergy Marine, Anglo-Eastern, Fleet Management and Scorpio.
• Shipyards and repair: Cochin Shipyard, Mazagon Dock, Garden Reach, Hindustan Shipyard and L&T Shipbuilding — hot work permits, gas-free certification, dry dock fire watch, commissioning of fixed systems.
• Survey and classification: Indian Register of Shipping, DNV, Lloyd's Register and ABS surveyors verifying SOLAS/FSS/LSA compliance; DG Shipping surveyors and flag/port State inspectors.
• Ports, offshore and terminals: tanker terminals at Jamnagar, Sikka, Vadinar, Paradip and JNPT; ONGC offshore platforms and FSUs, where H-class divisions, deluge and gas detection apply.
• Training and compliance roles: STCW Basic and Advanced Fire Fighting instructors at DG Shipping-approved maritime institutes, safety officers and designated persons ashore under the ISM Code.
• Design and equipment supply: fire detection and CO₂ system manufacturers, foam concentrate and extinguisher makers supplying to IS and IMO/MED type approval.

Interview questions

• Q: What is the fire triangle and how does each extinguishing method relate to it? A: Fuel, oxygen and heat; water removes heat, CO₂ and foam remove oxygen, closing a fuel valve removes fuel, and powder breaks the chain reaction in the tetrahedron model.
• Q: Why must marine fuel oil have a flash point above 60 °C? A: Below that, vapour can flash at normal storage and bunkering temperatures in a confined ship; SOLAS therefore sets 60 °C closed cup, with a 43 °C allowance only for emergency generator fuel in specified arrangements.
• Q: Where is the emergency fire pump located and why? A: Outside the machinery space, with its own prime mover, fuel and sea suction, so that a fire in the engine room cannot disable the water supply.
• Q: What precautions precede a CO₂ release into the engine room? A: Account for every person and evacuate, stop all fans and the main engine, close dampers, skylights, doors and quick-closing fuel valves, then operate the two-stage release after the alarm and delay, and keep the space sealed with boundary cooling.
• Q: How much CO₂ is required for a machinery space? A: Free gas equal to 40% of the space volume excluding the casing, or 35% including the casing, whichever is greater, with 85% discharged within two minutes.
• Q: Difference between an EEBD and an SCBA? A: The EEBD is a short-duration (at least 10 minutes) escape-only hood that must never be used to fight a fire; the SCBA is a refillable working set, typically 1,200 litres giving about 30 minutes.
• Q: What is a hydrostatic release unit and when does it operate? A: It secures a liferaft to the cradle and releases it by water pressure at roughly 1.5-4 m depth if the ship sinks, so the raft floats free and inflates on its painter.
• Q: What are A, B and C class divisions? A: A-class is steel, flame and smoke tight for 60 minutes with insulation grades A-60 to A-0; B-class is non-combustible and flame tight for 30 minutes; C-class is only non-combustible with no integrity requirement.
• Q: Why is water the wrong medium for a galley deep-fat fryer fire? A: The oil is far above 100 °C, so water flashes to steam and ejects burning fat violently; wet chemical is used because it saponifies the fat and forms a sealing layer.
• Q: How does an inert gas system prevent tanker fires? A: By keeping cargo tank oxygen below 8% by volume at positive pressure, the vapour space is too oxygen-poor to burn regardless of hydrocarbon concentration.
• Q: What causes a crankcase explosion and what protects against it? A: A hot spot creates an oil mist that ignites, giving a primary and possibly a secondary explosion; oil mist detectors, bearing temperature monitoring, non-return relief doors and never opening the crankcase immediately after an alarm are the safeguards.
• Q: What drills does SOLAS require and how often? A: Fire and abandon ship drills monthly on cargo ships, within 24 hours of sailing if more than a quarter of the crew changed, each lifeboat lowered and manoeuvred in the water at least every three months, plus enclosed-space entry and rescue drills every two months.
• Q: What is boundary cooling and why continue it after the fire is out? A: Cooling adjacent bulkheads and decks with water to stop conducted and radiated heat igniting neighbouring spaces, and to prevent re-ignition since CO₂ provides no cooling.

Common mistakes

• Quoting 40% of the whole engine room including the casing — the two CO₂ rules are 40% excluding the casing and 35% including it, and the larger result governs.
• Forgetting to convert a CO₂ volume to mass (divide by 0.56 m³/kg or multiply by about 1.8 kg/m³) and then to whole cylinders rounded up.
• Treating CO₂ as a cooling agent; it only dilutes oxygen, so a space reopened early re-ignites.
• Using nozzle pressure in bar directly in √(2p/ρ) without converting to pascals, or using 1,000 instead of 1,025 kg/m³ without saying so.
• Confusing EEBD with SCBA in a drill or interview, or assuming an EEBD can be used to enter a space.
• Mixing up the flash point and fire point definitions, or quoting an open-cup value against the SOLAS closed-cup 60 °C limit.
• Listing foam or water for electrical fires, or water for a Class D metal or Class F cooking-oil fire.
• Writing that fixed systems are the first response — alarm, fuel isolation, ventilation shut-down and portable attack come first; total flooding is a last resort after the space is evacuated and sealed.

Related topics

Ship construction and stability · Naval architecture basics · Engine room watchkeeping · Marine auxiliary machinery: pumps and compressors · Marine pollution prevention and MARPOL · Industrial safety, risk assessment and HAZOP